Neuroectodermal and endodermal expression of the ascidian Cdx gene is separated by metamorphosis
Neuroectodermal and endodermal expression of the ascidian Cdx gene is separated by metamorphosis
复制标题
DOI：
10.1007/s004270050306
复制
发表时间：
2000-04-01
影响因子：
2.4
通讯作者：
Degnan, BM
中科院分区：
文献类型：
--
作者：
Hinman, VF;Becker, E;Degnan, BM
海鞘动物是一类无脊椎动物，呈现双相生活史，在胚胎发生(背侧神经管和脊索)和变态(咽鳃缝和内花柱)期间发育脊索特有的结构。在这里，我们鉴定了一个caudallCDX基因同源物Hec-CDX的表达。来自海鞘动物赫德马尼亚曲线虫。脊椎动物CDU基因在原肠胚以及发育中的神经管和内胚层的后部表达。HEC-CDX在原肠胚形成的最早阶段开始表达。RNA丰度的高峰首先出现在神经形成和尾芽伸展期间，然后出现在3-5日龄的幼虫身上。HEC-CDX在原肠胚晚期胚孔前唇的一对细胞中表达，这些细胞构成了神经板的最后面部分。在尾芽形成期间，表达在这些细胞中保持，并且仅限于这些细胞。在变态过程中，表达定位于幼鱼的肠道。这些数据和H.Curvata OTX基因的数据一起表明，新的海鞘双相身体计划的进化并不伴随着这些基因部署到新的途径中，而是伴随着组织特异性表达的时间分离。
Ascidians are a group of invertebrate chordates that exhibit a biphasic life history, with chordate-specific structures developing during embryogenesis (dorsal neural tube and notochord) and metamorphosis (pharyngeal gill slits and endostyle). Here we characterize the expression of a caudallCdx gene homologue, Hec-Cdx. from the ascidian Herdmania curvata. Vertebrate Cdu genes are expressed at gastrulation and in the posterior of the developing neural tube and endoderm. Hec-Cdx expression is initiated at the earliest stages of gastrulation. with peaks in RNA abundance occurring first during neurulation and tailbud extension and then in 3- to 5-day-old juveniles. Hec-Cdx is expressed in a pair of cells in the anterior lip of the blastopore in the late gastrula which form the most posterior portion of the neural plate. During tailbud formation expression is maintained in and solely restricted to these cells. During metamorphosis expression is localized to the intestine of the juvenile. These data, along with data for the H. curvata Otx gene, suggest that the evolution of the novel ascidian biphasic body plan was not accompanied by a deployment of these genes into new pathways but by a temporal separation of tissue-specific expression.